Research ArticleMATERIALS SCIENCE

High-contrast and reversible polymer thermal regulator by structural phase transition

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Science Advances  13 Dec 2019:
Vol. 5, no. 12, eaax3777
DOI: 10.1126/sciadv.aax3777

Abstract

In comparison with the advancement of switchable, nonlinear, and active components in electronics, solid-state thermal components for actively controlling heat flow have been extremely rare. We demonstrate a high-contrast and reversible polymer thermal regulator based on the structural phase transition in crystalline polyethylene nanofibers. This structural phase transition represents a dramatic change in morphology from a highly ordered all-trans conformation to a combined trans and gauche conformation with rotational disorder, leading to an abrupt change in phonon transport along the molecular chains. For five nanofiber samples measured here, we observe an average thermal switching ratio of ~8× and maximum switching ratio of ~10×, which occurs in a narrow temperature range of 10 K across the structural phase transition. To the best of our knowledge, the ~10× switching ratio exceeds any reported experimental values for solid-solid and solid-liquid phase transitions of materials. There is no thermal hysteresis observed upon heating/cooling cycles.

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

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